Lift and recline chairs typically comprise a floor support or base section, a chair structure that includes at least a seat section, a back section, and a footrest section, which components are usually pivotally connected together by any number of different linkage arrangements, and a lift-recline mechanism connecting between the floor support and chair structure for moving the chair between a raised lift position and a reclining position. The use of one or more separate electronic actuators to control the movements of the lift-recline mechanism and adjust the position of the chair structure is known. Until recently, however, there was no ability to adjust the angle or incline of the chair back or back section to any desired position within the range of motion allowed by the chair back actuator without requiring or resulting in the position of another component of the chair structure, primarily the seat frame or footrest, to also be moved or adjusted. This is because movement of one or more parts of the back frame actuator mechanism was impeded or obstructed by other parts or components of the chair. Therefore, despite the use of a separate chair back actuator, the position adjustability of the back frame was still limited.
In U.S. Pat. No. 7,543,885 and its related patent documents, all of which are owned by the Applicant, an arrangement is disclosed by which the position or angle of the back frame is adjustable without requiring movement of the seat frame or other chair components except for those components and linkages connecting the back frame and back frame actuator to the chair assembly. This was accomplished by connecting the back frame actuator between the back frame and the seat frame or a component that moves or travels with the seat frame as its position is adjusted using a separate actuator. Such arrangement allows the back frame actuator connection to in effect follow the movements of the seat frame as its position is adjusted, while the position of the back frame actuator in relation to the seat frame remained essentially unchanged.
None of these arrangements for connecting the back frame actuator to the chair assembly allowed the back frame actuator to be connected to the lift frame of the chair, however, or to other components of the chair assembly that do not travel or follow the movements of the seat frame, since movement of the chair into a lift position required the relative position of or distance between the components of the lift frame with respect to the back section to vary. Provision of an economical arrangement by which the back frame actuator is connected between the back frame and the lift frame or base while still allowing for independent movement of the back frame in any position was not thought to be possible due to the complex movements of these components in relation to the back frame. The present inventors have nevertheless unexpectedly discovered that by precisely and simultaneously controlling the movements and position of the lift/recline and back frame actuators, the back frame actuator can be connected between the back frame and lift frame or base while still allowing the chair assembly to be reclined into any reclining position, including the so-called Trendelenburg and zero gravity positions.